1. Field of the Invention
The present invention is related to wheelchairs. In particular, the present invention is related to braking devices for wheelchairs. More particularly, the present invention is related to braking devices which are actuated when a patient rises from the wheelchair.
2. Description of the Related Art
Getting in and out of a wheelchair is a dangerous task for patients. Physically and mentally disabled people are injured when they attempt to get out of, and especially into, the wheelchair without an attendant or nurse to assist them because the wheelchair rolls away from them as they attempt to rise from the wheelchair.
Injuries suffered by patients exiting wheelchairs are particularly prevalent among the mentally impaired. A mentally impaired patient told by a nurse to stay in the wheelchair until an attendant is summoned may forget the nurse's warning shortly after the nurse leaves the patient. Such occurrences commonly occur in homes for the elderly where there are many patients suffering from Alzheimer's disease and other mental frailties.
Braking assemblies for wheelchairs are known in the art. Exemplary of the braking assemblies of the prior art are those disclosed in the following U.S. Patents:
U.S. Pat. No. 4,623,043 discloses an automatic wheelchair brake which automatically locks both wheels when a patient attempts to rise from the wheelchair. While seated the patient manually operates a three-way lever brake with manually locked, manually unlocked and automatic positions. If the patient attempts to rise while the brake lever is in the manually unlocked position, the lever automatically returns to the automatic position and both wheels still lock automatically. After the patient has exited, the wheelchair may easily be moved by shifting the operating lever to the manual unlock position.
U.S. Pat. No. 4,320,818 discloses a wheelchair brake assembly for use with a conventional foldable wheelchair which provides a pair of rearwardly extending brake arms connected to adjacent side frames underneath the seat. Each brake arm includes a transverse forward portion pivoted to the side frame and having a brake shoe biased into engagement with a drive wheel. The rearward portion of each brake arm is provided with a post engageable by the wheelchair seat to pivot the brake shoe out of engagement with the wheel when the seat is depressed and moved downwardly by the weight of an occupant. The wheelchair side frames are connected by a tension spring to ensure that the brake is engaged when the wheelchair is unoccupied.
U.S. Pat. No. 3,529,700 discloses a brake assembly for wheelchairs including spring loaded brake elements mounted on the main frame of a wheelchair and biased toward wheel engagement. The elements are disengaged from the wheels in response to a seat controlled linkage or manually operable disengagement device.
U.S. Pat. No. 3,302,757 discloses an automatic immobilizing device in a wheelchair having a frame and a chair supported by at least two wheels rotatably mounted to either side of the chair, the improvement including two elongated lever members each pivotally mounted at one end to the frame, each lever member being substantially horizontally positioned, one each of the lever members being positioned adjacent one each of the wheels and each being disposed to engage and immobilize the adjacent wheel when urged pivotally downwardly; a spring assembly operatively connected to and disposed to urge each lever pivotally downwardly into engagement with the wheels; and a belt attached at either end to one of the levers, being suspended from the frame and extending across the levers from engaging and immobilizing the wheels when sat upon by a person and of such length that the spring urges the levers into engagement with the wheels when a person rises from the belt.
U.S. Pat. No. 2,259,924 discloses a braking device for invalid chairs having forward and rearward supporting wheels, a seat section movable about an approximately horizontal axis located between the forward and rearward wheels; at least one leg carried by the seat section forward of the axis, and a braking device for one or more of the rearward wheels connected with the seat section; the seat section being movable about the axis under control of an occupant of the chair to thereby shift both the leg and the braking device from an active position to an inactive position and vice versa.
U.S. Pat. No. 2,053,852 discloses a mechanical chair which is a combination of a frame; a seat pivoted adjacent its forward edge to the frame; a rotatable member having bearings in the frame and connected by an operating rod to the seat to raise and lower the latter about its pivot; a motor operatively connected to and rotating the member; a stopping device carried by the member operative to stop the actuation of the motor when the seat is in its extreme raised and lowered positions; and a manually operated actuation device for initiating actuation of the motor after it has been stopped.
My U.S. Pat. No. 5,203,433 discloses an automatic braking wheelchair having an automatic braking assembly which automatically locks one or both wheels of a wheelchair when the patient attempts to rise.